Economic, thermodynamic, environmental, and inherent safety investigation of heat pump-assisted extractive dividing wall column for separating binary azeotrope

Abstract

Inherently safer design during the preliminary design stage is vital to reduce the potential risks and accidents of new process design. So far, little effort has been paid to incorporating inherent safety assessment into the techno-evaluation of heat-integrated extractive dividing wall column processes toward sustainable development. To this end, this paper proposes a systematic methodology for designing the energy-efficient extractive dividing wall column processes by applying heat pump and feed preheating techniques to separate binary azeotrope. The proposed approach gradually recovers the waste heat within the process, and the separation of acetonitrile and water is selected as a case. The results show that the total energy consumption, total annual cost, and the CO2 emissions of heat-integrated extractive dividing wall column processes are significantly reduced compared to conventional design, and the thermodynamic efficiency is simultaneously improved. In the process evaluation stage, the inherent safety analysis is performed regarding the Process Route Index and Process Stream Index. Such indices give insights into process safety performance in terms of the overall process and individual streams. The results of the inherent safety investigation show the intensified extractive dividing wall column by a single heat pump performs better than the dual heat pump-assisted process. This multi-criterion evaluation demonstrates a trade-off between inherent safety performance and energy saving in applying a heat pump system in conjunction with the distillation process.